Rs-232 Serial Interface - Epson C31CE94061N Technical Reference Manual

When using the SDK from Epson, this connection process is not necessary.
The iOS application cannot receive the data sent from the printer
Situation
Although the printer sends data to the iOS device and the data is received by the iOS device, depending on the
combination of the iOS version and the iOS device, the iOS application may not be able to receive the data.
Conditions
This may occur in combinations of the following conditions.
 iOS version: 7.1, 7.1.1
 iOS device: iPhone 5s, iPhone 5c, iPhone 5, iPad Air, iPad mini 3, iPad (4th generation), iPad mini, iPod
touch (5th generation), iPhone 4s, iPad (3rd generation), iPad 2
 Application processing: If the Bluetooth port is closed and then reopened while the application is running.
Solution
The solution differs depending on the iOS device being used. See the following table.
iOS Device
iPhone 4s
iPad (3rd generation)
iPad 2

RS-232 Serial Interface

Interface board specifications (RS-232-compliant)
Item
Data transfer method
Synchronization
Handshake
Signal level MARK
SPACE
Bit length
Transmission speed
[bps: bits per second]
128
This situation can be avoided by using the Epson ePOS SDK for iOS.
Serial
Asynchronous
Select one of the following with DIP switch 1-3:
 DTR/DSR
-3V to -15V logic "1"/OFF
+3V to +15V logic "0"/ON
Select one of the following with DIP switch 1-4:
 7 bit
 Select one of the following with DIP switch 1-7/1-8:
4800/9600/19200/38400 bps
 Select one of the following with commands:
2400/4800/9600/19200/38400/57600/115200 bps
Solution
Specifications
 XON/XOFF
 8 bit